Move QML files to src/qml and don't use internal qml modules

src/qml/Settings/About.qml

@@ -0,0 +1,12 @@
+// SPDX-FileCopyrightText: 2020 Tobias Fella <fella@posteo.de>
+// SPDX-FileCopyrightText: 2021 Carl Schwan <carl@carlschwan.eu>
+// SPDX-License-Identifier: LGPL-2.0-or-later
+
+import org.kde.kirigami 2.15 as Kirigami
+
+import org.kde.neochat 1.0
+
+Kirigami.AboutPage {
+    title: i18nc("@title:window", "About NeoChat")
+    aboutData: Controller.aboutData
+}